A CONCEPT OF A POLARIZED POSITRON SOURCE FOR A LINEAR COLLIDER

摘要

We propose a design of polarized positron source for a linear collider. The design is based on electron-positron pair creation from backward-Compton scattered laser photons. Polarized 7-rays are created from Compton scattering of circularly polarized laser-light off high energy electron beam. Those 7-rays subsequently create polarized positrons on a thin conversion target. A future linear collider of TeV-energy region requires large number of positrons in a very short pulse. Those short pulses are required to repeat in a complicated time-structure. To meet those requirements, we will employ a high current electron linac of 5.8 GeV and 50 of high power CO_2 lasers. A off-axis parabolic mirror which have a hole at it's center is employed at the collision point of a electron beam and each laser beam, in order to achieve an efficient head-on collision. In our design, positron polarization of 60 % will be available.